Electricity: electrical systems and devices – Safety and protection of systems and devices – Motor protective condition responsive circuits
Reexamination Certificate
2001-02-06
2003-08-05
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Motor protective condition responsive circuits
C361S023000, C361S093100
Reexamination Certificate
active
06603644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a motor-driven curtain assembly, more particularly to a motor control device that can provide overload protection to a motor of a motor-driven curtain assembly.
2. Description of the Related Art
Referring to
FIG. 1
, a conventional motor-driven curtain assembly
1
is shown to comprise a longitudinally extending hollow top rail
10
, a longitudinally extending drive shaft
12
mounted rotatably in the top rail
10
, a motor
15
for driving rotatably the drive shaft
12
, a plurality of first hook members
11
mounted slidably on a bottom side portion of the top rail
10
, a pair of second hook members
13
mounted threadedly on the drive shaft
12
, a pair of curtain pieces
14
, each of which has a top end that engages a respective set of the first hook members
11
and a respective one of the second hook members
13
, pairs of first and second optical sensors
161
,
162
mounted in the top rail
10
for limiting operation of the motor
15
during closing and opening movement of the curtain pieces
14
, and a switch unit
17
for controlling operation of the motor
15
.
In use, when a CLOSE key
171
on the switch unit
17
is operated, the motor
15
will be activated to drive the drive shaft
12
to rotate in a positive direction. The second hook members
13
are mounted respectively on externally threaded sections of the drive shaft
12
that are threaded in opposite directions. As such, rotation of the drive shaft
12
in the positive direction will result in axial translation of the second hook members
13
along the drive shaft
12
toward each other. Because each of the second hook members
13
is connected to the leading edge of a respective one of the curtain pieces
14
, movement of the second hook members
13
toward each other will result in corresponding movement of the curtain pieces
14
toward each other to a closed position. When the second hook members
13
reach the vicinity of the first optical sensors
161
, which are disposed at the intermediate portion of the top rail
10
, the first optical sensors
161
will generate an inhibit signal for deactivating the motor
15
, thereby completing the closing operation of the curtain assembly
1
.
Accordingly, when an OPEN key
172
on the switch unit
17
is operated, the motor
15
will be activated to drive the drive shaft
12
to rotate in a negative direction opposite to the positive direction. Rotation of the drive shaft
12
in the negative direction will result in axial translation of the second hook members
13
along the drive shaft
12
away from each other, thereby moving the curtain pieces
14
away from each other to an open position. When the second hook members
13
reach the vicinity of the second optical sensors
162
, which are respectively disposed adjacent to the opposite end portions of the top rail
10
, the second optical sensors
162
will generate an inhibit signal for deactivating the motor
15
, thereby completing the opening operation of the curtain assembly
1
.
Some of the drawbacks of the aforesaid conventional curtain assembly
1
are as follows:
1. The motor
15
is deactivated only upon detection of the second hook members
13
by the first or second optical sensors
161
,
162
. When the motor
15
is activated to move the curtain pieces
14
to the closed position, and either of the curtain pieces
14
gets caught on an object such that the curtain pieces
14
are prevented from reaching the closed position, the motor
15
will keep operating in the activated state. In order to overcome the increase in load resistance, the amount of electric current flowing through the motor
15
will increase, thereby leading to possible damage to the motor
15
due to overload.
2. Two pairs of optical sensors
161
,
162
are used to control deactivation of the motor
15
. Installation of the curtain assembly
1
is relatively complicated due to the electrical connection between the optical sensors
161
,
162
and the motor
15
, which requires the consumer to possess a certain amount of technical skill in order to be able to make such connections.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide a motor-driven curtain assembly having a motor control device that can provide overload protection to a motor of the curtain assembly and that dispenses with the use of optical sensors to simplify installation of the curtain assembly.
According to one aspect of the invention, a motor-driven curtain assembly comprises a longitudinally extending hollow top rail, a longitudinally extending drive shaft mounted rotatably in the top rail, a motor for driving rotatably the drive shaft, a curtain unit coupled to the drive shaft such that rotation of the drive shaft in a positive direction results in movement of the curtain unit to a closed position, and such that rotation of the drive shaft in a negative direction results in movement of the curtain unit to an open position, and a motor-control device that includes a driving circuit, a control unit, a current limiting circuit and an overload detector. The driving circuit is coupled to the motor for enabling rotation of the motor in the positive and negative directions. The control unit is coupled to the driving circuit and is operable so as to control the driving circuit to enable rotation of the motor in a selected one of the positive and negative directions. The current limiting circuit is adapted to couple the driving circuit to an external power source, and is adapted to limit current flow from the external power source to the driving circuit when the motor is subjected to an increase in load resistance. The overload detector, which is coupled to the control unit and the current limiting circuit, generates a control signal that is indicative of the amount of current flowing from the current limiting circuit to the driving circuit and that is provided to the control unit, thereby enabling the control unit to deactivate the driving circuit for stopping operation of the motor when overloading of the motor occurs.
According to another aspect of the invention, a motor-control device is adapted to be used in a motor-driven curtain assembly that includes a longitudinally extending hollow top rail, a longitudinally extending drive shaft mounted rotatably in the top rail, a motor for driving rotatably the drive shaft, and a curtain unit coupled to the drive shaft such that rotation of the drive shaft in a positive direction results in movement of the curtain unit to a closed position, and such that rotation of the drive shaft in a negative direction results in movement of the curtain unit to an open position. The motor-control device comprises:
a driving circuit adapted to be coupled to the motor and adapted to enable rotation of the motor in the positive and negative directions;
a control unit coupled to the driving circuit and operable so as to control the driving circuit to enable rotation of the motor in a selected one of the positive and negative directions;
a current limiting circuit adapted to couple the driving circuit to an external power source, and adapted to limit current flow from the external power source to the driving circuit when the motor is subjected to an increase in load resistance; and
an overload detector, coupled to the control unit and the current limiting circuit, for generating a control signal that is indicative of the amount of current flowing from the current limiting circuit to the driving circuit and that is provided to the control unit, thereby enabling the control unit to deactivate the driving circuit for stopping operation of the motor when overloading of the motor occurs.
REFERENCES:
patent: 4191915 (1980-03-01), Johansson
patent: 4363513 (1982-12-01), Sahar
patent: 5566644 (1996-10-01), Beery
Jackson Stephen W.
Rosenberg , Klein & Lee
LandOfFree
Motor-driven curtain assembly and motor control device therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Motor-driven curtain assembly and motor control device therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Motor-driven curtain assembly and motor control device therefor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3115973